Adiabatic and diabatic representations of potential energy curves for the (NaRb)+ system

Potential energy curves of (NaRb)+ are investigated by an ab initio one-electron approach. The inner electrons are modelled by non-empirical relativistic pseudopotentials. The core polarization potential is included and the deviation of the core-core interaction from 1R has been corrected. The spectroscopic constants of the ground (1 2Σ+) and lowest excited bound states (2 2Σ+, 3 2Σ+, 4 2Σ+, 1 2Π) are derived. From an analysis of the adiabatic electronic wavefunctions a qualitative diagram of diabatic electronic energies in the range of internuclear distances (4−40 a0) is made. A diabatic electronic basis for the (NaRb)+ molecular system is defined and electrostatic coupling matrix elements have been calculated.